multicellular organisms? You betcha!


With modern gene sequence analysis we've learned that by the natural replicating and splicing of various genes or parts of genes, enzymes of more complex organisms with modified functions are derived from the enzymes of more primitive organisms. In addition, a simple cell such as yeast has 30 per cent of its genome devoted to junk DNA, and complex cells such as our own have 98 per cent junk DNA. You guessed it. Junk DNA contains the control genes that specify how functional genes are turned on and off without actually changing the heritable DNA of the cells.


DNA occurs with a double strand of base pairs that operate something like a zipper. To replicate DNA during cell division, the zipper opens and complementary base pairs are laid down to create two strands of DNA from the first. Similarly, to transcribe mRNA, the DNA unzips and a string of complementary mRNA bases is synthesized.


At the beginning of each


functional DNA template there is a region with several cytosine and guanine bases. In order to silence a gene, the control gene adds a methyl group (just a single carbon atom and three hydrogens) to the cytosine and effectively blocks mRNA production, like jamming a piece of thread into a zipper. There are other methods of enhancing or suppressing gene expression by modifying the protein coating (histones) of chromosomes. Since this modification is heritable within replicating cells, it only takes one modified cell to create a complete tissue such as a stem or root.


In a seed, primordial cells are able to express all genes. They are pluripotent. Soon after germination, thousands of genes are selectively silenced and specialized tissues begin to develop.


We all know what happens next but, until recently we didn't know how.


— Back issues of BC Fruit Grower are available at


www.omedia.ca/grower/ 22


KELOWNA PUBLIC ARCHIVES PHOTO NO. 3689 Coldstream Ranch orchards and chicken coops, circa 1903.


Looking Back By Wayne Wilson


eginning in the early 1890s, Lord and Lady Aberdeen’s Coldstream Ranch east of Vernon played an important role in the development of the Okanagan region’s tree fruit industry. Comprising well more than 10,000 acres, the estate clearly had the land base to establish a viable orcharding enterprise that could be backed up by other crops and livestock income to help level out the cash flow. The influence of the Lord and Lady went beyond their actual orchards, mixed farming operations, and cattle ranching interests, however. First, parts of their ranch were subdivided into orchard lots and sold to a largely British Isles immigrant group. Each of these new orchardists, in turn, brought their own financial investment and business expertise to the region. Second, the sheer dimensions of the Coldstream Ranch brought significant income to the north Okanagan. Finally, serving as Canada’s Governor


B


General in the mid- 1890s, Lord Aberdeen’s


connection to the region would almost certainly have had a positive influence on the


emerging agricultural potential of the entire Okanagan Valley.


Curiously, there is historical argument about just how successful the Coldstream Ranch’s orchard operations were in the end. There is much more agreement, however, that the ranch played a critical role in shifting the region’s agricultural economy from cattle ranching and grain growing to the tree fruit industry. If you have photos or artefacts of our rich agricultural heritage, please contact the B. C. Orchard Industry Museum at 778-478-0347.


— Wayne Wilson is the former executive-director of the B.C. Orchard Industry Museum and the B.C. Wine Museum.


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British Columbia FRUIT GROWER • Fall 2014


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